Most vehicles, such as automobiles, include adjustable electrical, mechanical, and electromechanical systems that perform various functions. One such system is an adjustable pedal system for a vehicle, which includes one or more control pedals for the vehicle, such as an accelerator pedal, brake pedal, and/or a clutch pedal. In recent years, adjustable pedal systems have gained considerable market acceptance, particularly in the automotive industry. Adjustable pedal systems provide mechanisms and controls for adjusting the position of the control pedals in relation to the driver's position within the vehicle. The relative height of the control pedals can therefore be adjusted to accommodate multiple drivers each having differing anatomic dimensions and relative body proportions.
Presently known vehicle pedal adjusting mechanisms typically utilize a single motor operatively connected to two control pedals via two separate adjustment mechanisms. One of the pedals is typically connected to the motor via a worm gear train or other gear mechanism and the other pedal is typically connected to the motor via a flexible cable. While this type of system provides relative adjustment between the two pedals, it does not provide a sensor for monitoring the relative positions of the two pedals. In the event of a mechanical failure of only one of the two mechanisms, a serious safety hazard would be created if the driver were to adjust the pedal having the properly functioning mechanism substantially out of position with respect to the pedal having the defective mechanism.
Provisional patent application Serial No. 60/164,434, filed on Nov. 9, 1999 and assigned to the Assignee of the present invention, discloses an electromechanical pedal adjustment system. The system utilizes two linear motion safety switches each adapted to be mechanically connected between one of the pedals and a yoke that is pivotally connected to the pedal. Each of the switches are operable through linear movement created by movement of the pedal with respect to the yoke. Each switch includes linearly moveable contactors and associated contacts that are spaced apart along the length of the switch travel. The contactors and the contacts are part of an energizing circuit for the pedal adjusting motor that is only operable when the pedals are adjusted to the same, or nearly the same height. Thus, if a fault develops in the switches or an electrical circuit, the circuit is de-energized so that the motor will not operate until the system is repaired. While this type of system prevents substantial misalignment of the pedals, it does not provide for determination of absolute positioning of the pedals.
Another presently known system utilizes a potentiometer (often referred to as a “pot”) to monitor the height of the pedals. In this type of system, a pot is operatively connected to each pedal to create an output voltage that is proportional to the position of the pedal. The pot is mechanically coupled to an armature of a pedal adjustment motor by means of a large ratio gear train. The gear train reduces the number of revolutions the motor will normally rotate during complete travel of the pedals within their range of movement (typically several hundred revolutions) to less than one revolution. Thus, complete travel of the pedal from one end of its moveable range to the other corresponds to less than one revolution of the pot. When the pedal is adjusted via the motor, the motor also causes rotation of the contactor of the pot, thereby creating a variable voltage signal. The output voltages of each of the pots are compared by electronic circuitry to determine the difference between the output voltages. If the voltage difference exceeds a predetermined level corresponding to a fault condition, the motor is de-energized so that no further adjustment of the pedals is possible until the fault condition is addressed and/or repaired by a technician.
A significant disadvantage of this system is that failure of any of the mechanical linkage components between the motor and the pedal, such as the flexible drive cable, worm gears, pinions, drive clevis, etc., cannot be detected. This is because the pot is coupled to the motor. If the cable were to break and render one of the pedals adjustably inoperable, the pot would still generate a variable voltage signal. Thus, the motor could still be commanded to adjust the functioning pedal and the fault in the system would remain undetected.
Another disadvantage of this particular system is the complexity and relative high cost to manufacture and assemble the gear train requiring the large gear reduction.
Yet another disadvantage of this particular system is that it does not have an environmental seal adequate for most automotive applications. Exposure to various environmental conditions can cause failure of one or more electrical elements of the system and possibly create an intermittent or open electrical circuit. For example, during typical winter conditions when salt is utilized to melt ice and snow on the roads, salt water vapor may enter the electrical contact region of the pot and cause corrosion of the contacts. As an additional example, if the vehicle is used in dusty or dirty conditions, such as those found on a construction site or in the desert, airborne particulate matter may enter the pot and cause malfunction of the system.
The present invention solves all of the aforementioned problems and provides a robust design for a sensor of a vehicle pedal adjustment system.